Method of treating waste of benzol recovery



- Patented Apr. 2], 192 5.

UNITED STATES I i,534,55i PATENT crates.

FRED W. WAGNER, OF PITTSBURGH, PENNSYLVANIA, ASSIGNOR TO JONES 6t LAUGH- LIN' STEEL CORPORATION, OF PITTSBURGH, PENNSYLVANIA, A GOR-PQRATIO-N OF PENNSYLVANIA.

No Drawing.

To all whom it may cmwem:

Be it known that I, FRED W. WAGNER, residing at Pittsburgh, in the county of Allegheny and State of Pennsylvania, a citizen 5 f the United States, have invented or discovered'certain new and useful Improvements in Methods of Treating Waste of Benzol Recovery, of which improvements the following is a specification.

My invention relates to the disposal of by-products of coke distillation.

In the recovery of by-products in the industry alluded to, the coke-oven gas is scrubbed, that is to say, is under suitable la and predetermined conditions of pressure and temperature, brought into intimate mixture with an absorbent menstruum, ordinarily a heavy oil of the paraffin series, de-

rived from, or perhaps consisting of, petro- W leum. By such mixture the vapors of certain normally non-gaseous substances, present in the gas, are absorbed by the menstruum, and the denuded gas passes on, to serve such purposes as may at the particu- 25 lar place and under the particular circumstances, be found expedient. The menstruum with its burden of absorbed substances is distilled, ordinarily in a steam still, at a temperature of 150 0., and a distillate is thus obtained which is known as light oil. The menstruum remains in the still, and may be taken and used again. Or the ste s of absorption and distillation may be per ormed in continuity upon a continuously circulating stream of menstruum.

From the light oil so obtained benzol,

toluol and the xylols (solvent naphthas).

are derived by fractionation. The residue from this fractionation is essentially the absorbent oil which in relatively small quantities passes over with the distillate in the initial distillation.

The fractions of b'enzol, toluol, and the xylols require first to be washed, before there are marketable. To this end they are treated, each by itself, with sulphuric acid, for the separation of impurities, then they are heutralized, and then subjected a ain to distillation. The distillate is of mar etable purity. The residue in the still is, at the present time waste. All that I. have up to this point described is known to the art. My invention deals with this waste, and beginning with it I shall describe my invention.

viscosity of the ultimate product.

METHOD OF TREATING WASTE 0F BENZOL RECOVERY.

Application filed April 25, 1923. SeriaLNo. 634,604.

This residue consists essentially and chiefly of coumarone (compounds of the C H O type), and with it lesser quantities of naphthalene, oils of high boiling point,

sulphonated products, but no substantial quantity of the absorbent oil with which the coke-oven gas initially was caused to mingle.

However, I preferably modify somewhat the operation which as ordinarily conducted I have outlined. Beginning with the light oil, instead of fractionating and washing the fractions, I preferably wash the light oil and fractionate the so purified article. Subsequent washing of the so separated benzol, toluol, and xylols is not requisite. But it is with the residue that I have to do.

I treat the light oil with sulphuric acid in usual manner, then neutralize in usual manner, and then fractionate. The residue is principally coumarone, with some naphthalene, some high-boiling point oils, some sulphonated products. The ingredients are essentially the same as those found in the residues derived from the usual practice as,

outlined above though the proportions are somewhat different, with consequences which presently I shall indicate.

To this residue I add water and then a petroleum oil of specific gravity from .8 to .9. Preferably the oil which I here add is such oil as is used for the initial ab sorption, having specific gravity of from .83 to .86. I add this to the amount of I'bring the whole to a temperature of C. and then allow it to cool and stand for 48 hours. An emulsion is produced, and by standin a gravitational separation takes place. he lighter oil above is decanted ofl",'and a semi-solid mass remains.

This remaining semi-solid mass is heated, and, because of the presence of water within and forming part of the emulsion, a steam distillation ensues. The heating is continued until the water is entirely driven off and a temperature of 18020O C. attained. The heat is then shut off and the oil which before the immediately preceding steam distillation had been decanted off is now returned, in quantity suflicient to give a finished product of proper consistency for the intended purpose. This quantity will be greater or less. depending upon the variable condition of viscosity which in practice exists, and according to the desired Ordinarily, the amount of oil so returned will be more or less, of the total volume.

When the oil has been so returned to the mass the whole is allowed to stand for about five days, during which period a coagulabest, and is derived, as I now have made plain from a by-product commonly regarded as valueless andan annoyance, to make disposal of. v I

Manifestly the oil is useful generally where oils of its viscosity and associated physical properties are useful. And, as I have intimated, its viscosity and allied properties may be varied, by varying the portions in which the ultimate composition of ingredients is made.

I have said that I prefer, having produced light oil to wash before fractionation. I have explained, however, that the usual way to proceed is to fractionate the li ht oil, then wash the fractions, and then distill again. And I have explained that if this be done there will remain after such distillations,

residues which are still essentially coumarone compounds, with small associated quantitiesof other substances, such as I have named.

I may so proceed and so obtain my -cou'- marone residue, and in case I do so, -I proceed with it, in like manner as I proceedwith the coumarone residue of my preferred procedure, the only difference being that in the case I here am considering it is necessary in order to produce an oil of like consistency to add to the coumarone residue petroleum oil of .8 to .9 specific gravity in larger measure than I In a companion application filed by me on even date herewith, Serial No. 634,605, I

have described and claimed a method and the product thereof, which in large part is identical with the method hereindeseribed,

but specifically distinct from the invention herein claimed.

I claim as my invention: 1. The method herein described of deriving a by-product oilfrom the residuewhich remains after treating the light oil derived from coke-oven gas with, sulphuric acid, for the separation therefrom of benzol, toluol, and the xylols, such method consisting in adding to such residue petroleum oil and water, heating, then coollng, and allowing the mass to stand, then decanting off the lighter oil, subjecting the remaining semisolid mass to distillation, then adding oil to the residue, and allowing the mixture to coagulate. I

2. The method hereindescribed of deriving a by-product oil from the residue which remains after treating the li ht oil derived from coke-oven gas with sul uric acid, for the separation therefrom o benzol, toluol,

and the xylols, such method consisting in adding to such residue petroleum oil and water, heating, then cooling, and allowing the mass to stand, then decanting off the lighter oil, subjecting the remaining semisolid mass to distillation, returning to the mass previously decanted lighter oil, and allowing the resultant mass so compounded to coa ulate.

3. The herein described method of treating a residue containing coumarone which consists 111 adding .to it petroleum oil and 1 water, heating, allowing the mass to cool and settle, decanting, subjecting the 'remainmg semi-solid mass to distillation, then adding oil, and allowing coagulation to follow.

4:. The method herein described of treating to the residue previously decanted lighter oil, and allowing coagulation to follow.

In testimony whereof I have hereunto set my hand.

- FRED W. .WAGNER;

Witnesses JOHN NU'rrALL, Ronnn'r C. 'Knoen. 

